System of space discharge devices



Jan. 8, 1929. 1,698,558

A. A. OSWALD ET A1..

SYSTEM OF SPACE DISCHARGE DEVICES #Wen/ams s 40 AWM/f" A @awa/a fdn/am/Z. /l/e/Sa/y Jan. 8, 1929. 1,698,558

A. A. cJsWALDl ET AL sYsTEM oF SPACE DISCHARGE DEVICES Filed March 17, 1924 2 sheets-Sheet 2 'if /0l /f /f 4f n 22' gm fiez-31u E Patented Jan. 8, 1929.

narran srares F fr i Q E ARTHUR A. OSWALD AND EDWARD L. NELSON, EAST ORANGE, NEW JERSEY, AS-

SIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,

A CORPORATION OF NEW YORK.

SYSTEM OF SPACE DISCHARGE DEVICES.

Application lcd March 17, 1924. Serial No. 699,715.

This invention relates to systems of space discharge devices and more particularly to an arrangement'whereby a plurality of these devices may be connected in parallel withoutcausing the production of parasitic oscillations.

An object of this invention is to provide a more or less symmetrical arrangement of space discharge devices whereby inter-tube singing is prevented.

A further object is to provide a semi-symmetrical arrangement of space discharge tubes whereby the load may be equally distributed among the tubes.

A still further object is to provide an arrangement of space discharge tubes adapted to eliminate the tendency for the load distribution to vary with frequency variation.

In amplifier and modulator' or variable impedance space discharge tube systems where the tubes are mounted in a straight row, parasitio oscillations are set up which reduce the operating efficiency of the set; the load tends to be distributed unequally among the tubes with the result that some tubes burn out before others and in certain cases the load distribution varies with frequency variation.

The invention provides a system in which a plurality of'pa'rallel connected three electrodo space discharge tubes, arranged to constitute a unit or bank, are more or less symmetrically positoned with reference to the circuit connections for associating them with input and output apparatus.

In accordance with this invention, the tubes included in'each unitor bank have their input and output electrodes respectively connected to common bus bars, each of which defines a more or less symmetrical geometrical ligure.

The invention will be described below as applied to a system involving the constant current method for producing a carrier wave modulated in accordance with speech waves.

In the system to be described, the voice `frequency waves are raised to high power by means of a set of space discharge tubes connected in parallel to constitute a bank and the high power waves are supplied to the plate circuit of a similarly constituted bank of high frequency amplifiers. Space current is supplied to both banks of tubes in parallel from a direct current source through a high impedance choke coil which cooperates with the source so that the total currentsupplied to the system is substantially constant.

In this manner, the current supplied to the space path of the high frequency amplifying tubes is caused to vary in accordance with the low frequency waves, whereby a high frequency wave having its amplitude varied in accordance with speech frequency waves is produced.

For a complete understanding of the invention, reference should be made to the following description read in conjunction with the attached drawings in which:

Figs. 1 and 2 show radio transmitting systems including different embodiments of the invention, and y Figs. 3 and 4 illustrate side and plan views respectively ofthe apparatus shown iny Fig. 2.

Referring now to Fig. 1, there is shown diagrammatically a modulator-system including five discharge tubes and an amplifying system also including five discharge tubes, having the tubes arranged four at the vertices of a rectangle and one at a point constituting an extension at one side of the rectangle. v y

Circuit 10, including microphone 11 and source of direct current 12, represents a source of waves of speech frequency. Such waves are impressed upon amplifier 14 through the transformer 13. The amplied waves are then impressed upon the impedance control electrodes, or grids, of the modulator tubes 2O through the transformer 15 and grid bus bar 410 which is common .to the modulating tubes. l

VThe bus bar 40 is substantially U-shaped and theV grids of the tube are'connected at points spaced equidistant from each other on the arms of the U-shaped bus bar. Source 16, connected to the bus bar 40, supplies polarizing potential to the grids of the tubes 20.

Tubes 30, adapted to amplify high frequencywaves from the source`26, are arranged in a similar' manner.

Filament heating current for both sets of tubes is supplied by a source of alternating current 17 through the transformer 32 to the bus bars 27, 28, 29 and 31. vBus bars 27 and 28 are common to the tubes 20 and bus bars 29 and 31 are common to the tubes 30.

High frequency waves from the source 26 are impressed through vthe transformer 33 and the bus bar L11 upon the grids of the am- Heising. The iron core choke coil 2l included in the common portion of the supply circuits for thetubes and 30 cooperates with the source 18 to maintain the space current supvplied to the tubes 20 and 30 at a substantially constant value. f

The lead for connecting the plates of the tubes 20 to the common conductor, through which space current is supplied to the two banks ofV tubes is provided with an inductance 22. This inductance prevents high frequency oscillations flowing through the output circuit of tubes 30 from being impressed upon the plates of tubes 20.

A resistance 23 is included in the filament circuit of each device for controlling the flow of current through the filaments.

The lead including the coil 22 is connected to a common bus bar for the tubes 20. This bus bar constitutes a` closed rectangle with one lead as an extension at one side of the rectangle. y An inductance 24 is included in each of the leads connecting the bus bar 25 to `the plates of the tubes 20, for the purpose of reducing inter-tube singing.

in the amplifying system comprising tubes 30, the elements 35, 36, 37 and 41 correspond to the elements 23, 24 25 and 40 of the modulating system. The alternating current output circuit common to the amplifiers is y completed `by a capacity 38, which constitutes a path of low impedance for high frequency alternating current in. shunt to the source 18. Amplified waves from the plates ofthe tubes 30 are supplied to the antenna 42, from which they are radiated, through the transformer 39. n

Fig. 2 illustrates a modulator-ampliiier ar rangement similar to that' shown in Fig". 1 in which six discharge tubes are used 4in both the modulating and the amplifying systems'. In

. this arrangement amplified speech waves and polarizing potential are supplied `to the y grids of the tubes 2Ov through a common bus bar 40 in a: manner similar to that described in connection with Fig. 1.

The bus bar 40, in this case, is in the form of a closed ring. The filaments of tubes 2O are heated by current from the source 17 through the transformer 32. Current flows from one terminal of the secondary winding of trans-V former 32 through the resistance 23, the filament of each tube, the closed ring bus bar 27 messes.,

to ground and thence to the other terminal of the secondary winding.

Space current is supplied to the devices 20 through bus bar 25 extending lengthwvise between the two rows of devices. The direct current source 18 supplies .space current, through the iron core choke coil 43, to the tubes 20. A fuse 44 is included in the space current circuit of each tube to prevent eXcessive current being supplied to their space -from the source 17. Current flows from one terminal of the secondary winding of transformer 32 through the closed ring bus bar 29, the filaments of each of the tubes, resistance '35 and ground, to the other terminal of the transformer secondary. High frequency waves are supplied to the grids of the tubes 30 through the transformer 33 and the closed buss bar 81 common to the tubes.

Current is supplied to the plates of these tubes by a source of direct current 18 through the iron core choke coil 46 and indu'ctance coil 49. The plate current bus bar 37 is arranged similarly to the bus bar 25 for the modulating devices. Fuses 47 and jacks 48 correspond to, andare used forv 'the same purpose as, the elements 44 and 45 of the modulating system. p

High frequency waves from the plates of tubes 30 are transn'iitted to `the antenna 52, from which they are radiated, by the inductive coupling between the coils 49 and 50.

` A condenser 51 provides a path of low iinpedance for high frequency waves in shunt to the source 18. Capacity 53 provides a low impedance path for speech frequency waves in shunt to the choke coils 43 and'46. A high frequency choke coil 22 prevents waves from the amplifier 30being supplied to the tubes 20.

Figs. 3 and 4 illustrate the arrangement of the apparatus shown in Fig. 2. Since both the modulating and amplifying systems comprise ident-ical elements, arranged in the same manner with reference to the supporting panel and the tubes of the respective systems, a description of the relative positions of these elements with respect to the supporting panel and one of the modulating tubes 2O will sufiicev for b'oth systems.

As shown in Figs. 8 and 4, the apparatus is mounted upon a supporting panel 55. In Fig'. 3, the tube socket 54 and the jack 45 are mounted directly on the panel 55. Fuses 44 are held in clips 56 mounted upon the panel 57. Panel 57 is connected to and supported by the panel by means of brackets 58. The space current bus bar 25, the fila- Vment heating bus bar 27 and the grid potential bus bar 40 are rigidly connected to the panel by means of insulated supports, not shown. The jack 45 has connected thereto, both physically and electrically, the inductance coil 24. The connections between the bus bar 25 and the fuse panels 57, between these panels and the inductance 24 and jack 45, and the jack 45 and tube socket 54 are all rigid.

In Fig. 4, the relation of the various elements with respect to the tube socket is clearly shown. A section of the bus bar 25 has been omitted to allow the relative arrangement of the various features to beY clearly illustrated.

Current flows from the bus bar 25 through the connection 59 to the fuse contact 60, the fuse A44 to the fuse Contact 61, connection 62 to the inductance coil 24 and jack 45, from the jack 45 through the connection 63, to the socket terminal 64 and to the spring contact of the socket 54. Similarly, current flows from the bus bar 25 through the connection 59, fuse'contact 60, fuse 44, fuse contact 61', connection 62', inductance 24, jack 45 and connection 63 to the socket connection 64.

Since bus bars 27 and 40 are in the same vertical plane, only one is shown in this ligure. The bus bar 27 is connected to the spring contact 66 of the socket 54 and the bus bar 40 (not shown) is connected to the spring contact 67. Individual leads connect the source of filament heat-ing current to the spring'contact 68.

Attempts to secure satisfactory operation of systems of this type, having the tubes arranged in a row and their corresponding electrodes connected to bus bars having one end connected to the associated input and output apparatus, have. failed. When ,the energy to be transmitted is supplied to such a system, it has been impossible to obtain an equal distribution of the load among the tubes, and, in spite of the fact that a choke coil adapted to prevent intertube singing has been included in each of the leads connecting the plates of the tubes to the common bus bar, oscillatory voltages of considerable magnitude and of undesired frequencies have been produced in the plate bus bar. These conditions have prevented the system from operating efficiently.A

Moreover, they have at times caused the fuses included in certain of the plate leads to blow and at other times caused the tubes to fail.

While the cause of these disturbances has not been exactly determined, it would appear that they are probably due in large measure to the difference in the reactances of the conductive paths connecting the input and output apparatus to the electrodes of the different tubes.

This explanation is substantiated by the fact that systems having the tubes arranged in bank and having their electrodes'connected substantially symmetrically to the associated bus bars have been operated over an extended period. During the operation of these systems, the load was'found to be equally distributed among the tubes and no appreciable variation in the distribution of the load occurred when the frequency of the energy supplied to the systems was changed, no disturbing oscillations were produced in the plate bus bar, and the life of the tube was substantially uniform.

From the preceding description, it will be seen that this invention provides a simple arrangement adapted to Ieliminate the disadvantages inherent in systems including a number of space discharge devices connected in parallel, whereby systems of this type may be operated at materially increased efficiency as compared with the systems heretofore proposed.

lVhile in the preceding description, a certain application and specific details have been set forth for the purpose of completely andy clearly disclosing the nature of the invention, it is to be understood that this invention is not limited-to such disclosure but only by the scope of the attached claims.

lhat is claimed is:

1. A circuit including space discharge tubes in parallel which comprises a closed ring conductor of substantial diameter, and individual connections from several points on said ring to homologous electrodes of said tubes whereby said tubes are associated in substantial symmetry with said conductor.

2. A plurality of space discharge devices connected in parallel operating-relation, a closed circuit conductor of negligible resistance, connections'from homologous electrodes of said devices topoints on said conductor, whereby said devices are substantially symmetrical with respect to said conductor, and elements of small impedance individual to each connection.

3. A plurality of space discharge devices connected in parallel operating relation and spaced about in geometrical configuration, a closed ring conductor of dimensions substantially large as compared to the area outlined by said devices, and connections from homoloc gous electrodes of said devices to points on said conductor whereby said devices and conductor are substantially symmetrically related.

4. Asystem comprising a plurality of space discharge devices each having a cathode, anode and control electrode, a conductive system for connecting said devices with an external circuit in parallel operating relation, said conductive system comprising a conductor which provides a pair of parallel paths from each of the homologous electrodes of the discharge device to the external circuit, each of said pairs of paths having substantially the same impedance.

5. A system of vacuum tubes connected in parallel relation comprising a number of tubes arranged in rectangular formation with an additional tube forming an extension on one side of the rectangle, and a rectangular closed conductor having connections from each of said tubes tov said conductor.

6; A system comprising a plurality of vacuum tubes in rectangular formation having homologous electrodes connected to a closed substantially rectangular conductive path, in combination with another system of tubes arranged in rectangular relation with homologous electrodes connected to a substantially rectangular closed Conductive path, one of said systems functioning as a variable impedance means to modulate oscillations traversing the other system.

7. A system of vacuum tubes and aclosed conductor of negligible impedance associated therewith, said vacuum tubes connected to operate in vparallel having their grids connected to points upon said closed conductor of negligible impedance.

8.l A plurality of high frequency space discharge devices connected in parallel operating relation and spaced about in geometrical configuration, a' closed ring conductor of dimensionssubstantially large as compared to vthe area outlined by said devices, and connections from homologous electrodes of said devices to points on said conductor.

9'.- In a constant current modulation system, a plurality of space discharge devices connected in parallel operating relation, a closed circuit conductor of negligible resistance, connections from homologous electrodes of said devices to points on said conductor, and elements of small impedance individual to each connection.

lO. A high frequency amplication system comprising a plurality of space discharge devices each having a cathode, anode and control electrode,y a conductive system for connecting said devices with an external circuit in parallel opera-tingv relation, said conductive system comprising a conductor which provides a pair of parallel paths from each of the homologous electrodes of the discharge device to the external circuit, each of said pairs of paths having substantially the same impedance.

11. A space discharge system comprising a plurality of space discharge devices each having a cathode and a. grid control electrode, and an eXternasl'Circuit, common means for connecting the grid and the cathode 0f each of said devices to said external circuit, said means comprising two paths from said eXternal circuit to each of said electrodes of each of said discharge devices, the total length of the two paths between each electrode and the eX- ternal Circuit being the same for all of said devices.

12. A space discharge system comprising a plurality of space discharge devices 'having input and output circuits, an omnibus conductor and a circuit connected to said omnibus conductor, said discharge devices having homologous electrodes connected to said conductor through individual impedance elements, said discharge devices also having other homologous electrodes connected to said circuit, said circuit Comprising a pair of paths from the connection with said omnibus conductor to each of said second mentioned homologous electrodes, each of said pairs of paths utilizing the same portions of a common conductor in different parallel combinations cf substantially the same total impedance in the case of each pair.

In witness whereof, we hereunto subscribe our names this 7th da'y of March, A. D. 1924.

ARTHUR A. OSWALD. EDWARD L. NELSON. 

